1. Field of the Invention
The present invention relates to a temperature detector which detects a temperature of a detection object, and also to a recording apparatus including the temperature detector.
2. Description of Related Art
There is an ink-jet printer which prints an image on a recording paper by ejecting ink droplets on the recording paper as a recording medium. As such an ink-jet printer, one including a recording head and a driver IC is known. The recording head has a passage unit in which nozzle for ejecting ink droplets and pressure chambers communicating with the nozzles are formed, and an actuator unit which applies ejection energy to ink contained in the pressure chambers. The driver IC generates a pulse for driving the actuator. The actuator applies ejection energy to a pressure chamber by changing a volume of the pressure chamber. The actuator is driven by a pulsed drive signal being supplied from the driver IC.
In an ink-jet printer of this type, speedup of printing is attempted, by increasing a pulse frequency of a drive signal which is outputted from the driver IC and thereby shortening a cycle of ejection of an ink droplet. However, when a pulse frequency of a drive signal is increased, heat generation of the driver IC is also increased. Japanese Unexamined Patent Publication No. 2005-22294 discloses a technique by which when a driver IC reaches a predetermined temperature or more the driver IC stops driving until cooled down, to thereby restrain the driver IC from becoming too high in temperature. In this way, thermal destruction of the driver IC can be prevented. Further, Japanese Unexamined Patent Publication No. 2003-075264 discloses a temperature detection circuit which includes a diode and a comparator in order to detect a temperature of a driver IC. An output voltage of the diode changes depending on a temperature. The comparator detects that an output voltage from the diode agrees with a reference voltage or a standard voltage which corresponds to a detection temperature. According to this technique, it can be sensed that a temperature of the driver IC is a detection temperature at a time when the comparator detects that an output voltage from the diode agrees with the reference voltage. Here, there has been known a technique of outputting a reference voltage in the form of a sawtooth wave or a triangular wave and sweeping it. Application of this technique enables detection of a wide range of temperatures of the driver IC.